Conventionally, a hot water heater which warms an interior of a vehicle by using heat of engine coolant whose temperature has become high is usually adopted for a vehicle heater. Further, a heat pump cooler which cools air fed to an interior of a vehicle by using a low-temperature refrigerant of a heat pump is generally adopted for a conventional vehicle cooler.
Unexamined Japanese Patent Publication No. 10-76837 discloses a vehicle air conditioner which can enhance heating performance compared to a conventional vehicle air conditioner by using a heat pump based on a conventional hot water heater and adding a configuration of heating coolant of a hot water heater.